number theory
- To: mathgroup@smc.vnet.net
- Subject: [mg12491] number theory
- From: "Thomas A. Rice" <trice@earthlink.net>
- Date: Tue, 19 May 1998 13:31:54 -0400
- Organization: EarthLink Network, Inc.
I have been trying to use Mathematica to get integer solutions to
problems, but am beating my head against the wall.
Can one use Mathematica to give an exact solution in a situation like
the following?
An automobile travels at a speed exactly 20 times faster than John can
walk, but less than 65 mph. John walks exactly at a whole number speed
(integer) between 1 and 4 mph (1, 2, 3, or 4 mph). What are the speeds
the car might travel?
Answer: 20, 40, or 60 mph.
It doesn't work for me to enter:
Solve[{IntegerPart[walking] * 20 == driving, walking >0, walking < 5,
driving < 66}, driving]
I would be greatly indebted if someone could tell me if or how this
problem can be solved with Mathematica.